Medical procedures involving access to the brain through a burr hole in the skull are used to treat a variety of medical conditions. For example, electrical stimulation of the brain to relieve chronic pain, or for the treatment of movement disorders, may necessitate access via a burr hole. Similarly, burr holes are typically formed to allow implantation of a catheter, e.g., a parenchymal or intracerebroventricular catheter, to treat various ailments.
Use of a catheter to deliver a therapeutic agent to the brain generally involves the insertion of the catheter into the brain and dispensing the agent at the desired location. During a typical implantation procedure, an incision may be made in the scalp to expose the patient's skull. After forming a burr hole through the skull, the catheter may be inserted into the brain. To accurately place the catheter and avoid unintended injury to the brain, surgeons typically use stereotactic apparatus/procedures. One exemplary stereotactic apparatus is described in U.S. Pat. No. 4,350,159 to Gouda, which may be used to position, for example, an electrode.
As one can appreciate, once an inserted device such as a catheter is properly positioned, it is important that it be adequately immobilized to prevent movement from its intended location. Even minimal movement of the device tip may yield unsatisfactory therapeutic results. Accordingly, reliable methods and apparatus for anchoring and securing the device relative to the burr hole are needed.
Exemplary burr hole anchor devices include those described in U.S. Pat. No. 4,328,813 to Ray and U.S. Pat. No. 5,927,277 to Baudino et al. Ray discloses, among other features, a socket and plug arrangement in which the plug is positioned so as to trap a positioned electrical stimulation lead between the socket and plug. Baudino et al. discloses, among other features; an apparatus and method that allows anchoring of a device to occur before it is detached from the stereotactic apparatus, thereby reducing the potential for inadvertent movement during subsequent implantation steps.
While effective for their intended purposes, many known anchor devices are, for the most part, used primarily to secure the implanted catheter or lead for long term implantation. Some therapies (e.g., acute gene therapy for the treatment of Parkinson's disease), however, are delivered for a more limited period of time, e.g., a few hours to a few days or less. Accordingly, in the case of the latter, it may be beneficial to completely remove the catheter at therapy completion. Yet, device (e.g., catheter) removal generally requires a surgical procedure to: expose the burr hole and anchor; release the catheter from the anchor; remove the catheter; and close the incision. Such a removal procedure may, however, be undesirable for various reasons, including cost and potential patient apprehension associated with another surgical procedure.